Nonvolatile memory devices, erasing methods thereof and memory systems including the same

ABSTRACT

Provided are erase methods for a memory device which includes a substrate and multiple cell strings provided on the substrate, each cell string including multiple cell transistors stacked in a direction perpendicular to the substrate. The erase method includes applying a ground voltage to a ground selection line connected with ground selection transistors of the cell strings; applying a ground voltage to string selection lines connected with selection transistors of the cell strings; applying a word line erase voltage to word lines connected with memory cells of the cell strings; applying an erase voltage to the substrate; controlling a voltage of the ground selection line in response to applying of the erase voltage; and controlling voltages of the string selection lines in response to the applying of the erase voltage.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefits, under 35 U.S.C §119, of Korean Patent Application No. 10-2010-0114025 filed Nov. 16, 2010, the entirety of which is incorporated by reference herein.

BACKGROUND

A semiconductor memory device is a memory device which is fabricated using semiconductors such as silicon (Si), germanium (Ge), gallium arsenide (GaAs), indium phosphide (InP), and the like. Semiconductor memory devices may be classified into volatile memory devices and nonvolatile memory devices.

The volatile memory devices may lose stored contents at power-off. The volatile memory devices include a static RAM (SRAM), a dynamic RAM (DRAM), a synchronous DRAM (SDRAM), and the like. The nonvolatile memory devices may retain stored contents even at power-off. The nonvolatile memory devices include a read only memory (ROM), a programmable ROM (PROM), an electrically programmable ROM (EPROM), an electrically erasable and programmable ROM (EEPROM), a flash memory device, a phase-change RAM (PRAM), a magnetic RAM (MRAM), a resistive RAM (RRAM), a ferroelectric RAM (FRAM), and the like. The flash memory device may be generally divided into a NOR type and a NAND type.

Semiconductor memory devices with a three-dimensional array structure have been developed recently.

SUMMARY

One aspect of embodiments of the inventive concept is directed to provide an erase method of a nonvolatile memory device which includes a substrate and a plurality of cell strings provided on the substrate, each cell string including a plurality of cell transistors stacked in a direction perpendicular to the substrate. The erase method comprises applying a ground voltage to a ground selection line connected with ground selection transistors of the plurality of cell strings; applying a ground voltage to string selection lines connected with selection transistors of the plurality of cell strings; applying a word line erase voltage to word lines connected with memory cells of the plurality of cell strings; applying an erase voltage to the substrate; controlling a voltage of the ground selection line in response to applying of the erase voltage; and controlling voltages of the string selection lines in response to the applying of the erase voltage.

In some embodiments, the controlling a voltage of the ground selection line comprises keeping a voltage difference between a voltage of the substrate and a voltage of the ground selection line within a predetermined range.

In some embodiments, the controlling a voltage of the ground selection line comprises applying a ground selection line voltage to the ground selection line.

In some embodiments, a rising slope of the voltage of the ground selection line is controlled to be slower than that of the substrate.

In some embodiments, the controlling a voltage of the ground selection line comprises applying a ground selection line voltage to the ground selection line after the erase voltage is applied and a delay time elapses.

In some embodiments, the controlling a voltage of the ground selection line comprises floating the ground selection line after the erase voltage is applied and a delay time elapses.

In some embodiments, the controlling a voltage of the ground selection line comprises applying a ground selection line voltage to the ground selection line when a voltage of the substrate reaches a target voltage.

In some embodiments, controlling voltages of the string selection lines comprises keeping a voltage difference between a voltage of the substrate and voltages of the string selection lines within a predetermined range.

Another aspect of embodiments of the inventive concept is directed to provide a nonvolatile memory device which comprises a memory cell array including a substrate and a plurality of cell strings provided on the substrate, each cell string including a plurality of cell transistors stacked in a direction perpendicular to the substrate; an address decoder connected with the plurality of cell strings via a ground selection line, word lines, and string selection lines; a read/write circuit connected with the plurality of cell strings via bit lines; and a voltage generating circuit configured to supply an erase voltage to the substrate and a word line erase voltage to the word lines via the address decoder at an erase operation, wherein at the erase operation, the voltage generating circuit is further configured to control a voltage of the ground selection line and voltages of the string selection lines from a ground voltage in response to applying of the erase voltage to the substrate.

In some embodiments, the voltage generating circuit is further configured to keep a voltage difference between a voltage of the substrate and the voltage of the ground selection line within a predetermined range.

In some embodiments, the voltage generating circuit applies a ground selection line voltage to the ground selection line in response to the applying of the erase voltage and controls a rising slope of the voltage of the ground selection line to be slower than that of the substrate.

In some embodiments, the voltage generating circuit is configured to apply the ground selection line voltage at the same time with the applying of the erase voltage.

In some embodiments, the voltage generating circuit comprises an erase voltage generator configured to generate the erase voltage applied to the substrate in response to an erase enable signal; a delay configured to delay the erase enable signal by a predetermined time; and a ground selection line driver configured to generate a ground selection line voltage to be supplied to the ground selection line in response to an output signal of the delay.

In some embodiments, the voltage generating circuit comprises an erase voltage generator configured to generate the erase voltage applied to the substrate in response to an erase enable signal; a delay configured to delay the erase enable signal by a predetermined time; and a ground selection line driver configured to float a ground selection line voltage in response to an output signal of the delay.

In some embodiments, the nonvolatile memory device further comprises a substrate monitor circuit configured to activate a selection enable signal when a voltage level of the substrate reaches a target voltage level. The voltage generating circuit comprises an erase voltage generator configured to generate the erase voltage applied to the substrate in response to an erase enable signal; a gate circuit configured to AND the erase enable signal and the selection enable signal; a ground selection line driver configured to generate a ground selection line voltage to be supplied to the ground selection line in response to an output signal of the gate circuit.

In some embodiments, the voltage generating circuit keeps a voltage difference between a voltage of the substrate and the voltages of the string selection lines within a predetermined range.

In some embodiments, the memory cell array comprises a plurality of structures including conductive materials and insulation materials stacked in turn in a direction perpendicular to the substrate; and a plurality of pillars configured to penetrate the structures in the direction perpendicular to the substrate to contact with the substrate. The plurality of structures and the plurality of pillars constitute the plurality of cell strings.

In some embodiments, the memory cell array further comprises a plurality of doping regions provided at the substrate between plural of structures, the plurality of doping regions forming a common source line connected in common with the plurality of cell strings.

Still another aspect of embodiments of the inventive concept is directed to provide a memory system which comprises a nonvolatile memory device; and a controller configured to control the nonvolatile memory device, wherein the nonvolatile memory device comprises a memory cell array including a substrate and a plurality of cell strings provided on the substrate, each cell string including a plurality of cell transistors stacked in a direction perpendicular to the substrate; an address decoder connected with the plurality of cell strings via a ground selection line, word lines, and string selection lines; a read/write circuit connected with the plurality of cell strings via bit lines; and a voltage generating circuit configured to supply an erase voltage to the substrate and a word line erase voltage to the word lines via the address decoder at an erase operation At the erase operation, the voltage generating circuit is further configured to control a voltage of the ground selection line and voltages of the string selection lines from a ground voltage in response to applying of the erase voltage to the substrate.

In some embodiments, the nonvolatile memory device and the controller constitute a solid state drive (SSD).

BRIEF DESCRIPTION OF THE FIGURES

The above and other objects and features will become apparent from the following description with reference to the following figures, wherein like reference numerals refer to like parts throughout the various figures unless otherwise specified.

FIG. 1 is a block diagram illustrating a nonvolatile memory device according to some embodiments of the inventive concept.

FIG. 2 is a diagram illustrating a memory cell array in FIG. 1 according to some embodiments of the inventive concept.

FIG. 3 is a plane diagram of one of memory blocks in FIG. 1 according to some embodiments of the inventive concept.

FIG. 4 is a perspective view taken along a line I-I′ in FIG. 3 according to some embodiments of the inventive concept.

FIG. 5 is a cross-sectional view taken along a line I-I′ in FIG. 4 according to some embodiments of the inventive concept.

FIG. 6 is a diagram illustrating one of the cell transistors in FIG. 5.

FIG. 7 is a circuit diagram illustrating an equivalent circuit of a memory block described in FIGS. 3 to 6.

FIG. 8 is a diagram illustrating a voltage condition of a nonvolatile memory device in FIG. 1 at an erase operation.

FIG. 9 is a cross-section view of a memory block taken along a line I-I′ when channels of the ground selection transistors GST are formed.

FIG. 10 is a flowchart illustrating an erase method according to some embodiments of the inventive concept.

FIG. 11 is a flowchart for describing operations of controlling voltages of ground and string selection lines according to some embodiments of the inventive concept.

FIG. 12 is a diagram illustrating voltage variations corresponding to an erase method according to some embodiments of the inventive concept.

FIG. 13 is a block diagram illustrating a nonvolatile memory device according to some embodiments of the inventive concept.

FIG. 14 is a flowchart for describing operations of controlling voltages of ground and string selection lines according to some embodiments of the inventive concept.

FIG. 15 is a diagram illustrating voltage variations corresponding to an erase method described in FIGS. 10 to 14.

FIG. 16 is a block diagram illustrating a voltage generating circuit in FIG. 13.

FIG. 17 is a flowchart for describing operations of controlling voltages of ground and string selection lines according to some embodiments of the inventive concept.

FIG. 18 is a diagram illustrating voltage variations corresponding to an erase method described in FIGS. 10 to 17.

FIG. 19 is a block diagram illustrating a nonvolatile memory device according to some embodiments of the inventive concept.

FIG. 20 is a flowchart for describing operations of controlling voltages of ground and string selection lines according to some embodiments of the inventive concept.

FIG. 21 is a diagram illustrating voltage variations according to an erase method described in FIGS. 10 and 20.

FIG. 22 is a block diagram illustrating a substrate monitor circuit in FIG. 19.

FIG. 23 is a circuit diagram illustrating an up-trimmer in FIG. 22.

FIG. 24 is a block diagram illustrating a voltage generating circuit in FIG. 19.

FIG. 25 is a circuit diagram illustrating an equivalent circuit of a memory block in FIGS. 3 to 6 according to some embodiments of the inventive concept.

FIG. 26 is a circuit diagram illustrating an equivalent circuit of a memory block in FIGS. 3 to 6 according to some embodiments of the inventive concept.

FIG. 27 is a circuit diagram illustrating an equivalent circuit of a memory block in FIGS. 3 to 6 according to some embodiments of the inventive concept.

FIG. 28 is a circuit diagram illustrating an equivalent circuit of a memory block in FIGS. 3 to 6 according to some embodiments of the inventive concept.

FIG. 29 is a circuit diagram illustrating an equivalent circuit of a memory block in FIGS. 3 to 6 according to some embodiments of the inventive concept.

FIG. 30 is a circuit diagram illustrating an equivalent circuit of a memory block in FIGS. 3 to 6 according to some embodiments of the inventive concept.

FIG. 31 is a cross-sectional view taken along a line I-I′ in FIG. 3 according to some embodiments of the inventive concept.

FIG. 32 is a plane view illustrating a part of one of memory blocks in FIG. 2 according to some embodiments of the inventive concept.

FIG. 33 is a perspective view illustrating a memory block taken along a line I-I′ of FIG. 32.

FIG. 34 is a block diagram illustrating a memory system according to some embodiments of the inventive concept.

FIG. 35 is a block diagram illustrating an application of a memory system in FIG. 34.

FIG. 36 is a block diagram illustrating a computing system including a memory system described in FIG. 35.

DETAILED DESCRIPTION

The inventive concept is described more fully hereinafter with reference to the accompanying drawings, in which some embodiments of the inventive concept are shown. This inventive concept may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the inventive concept to those skilled in the art. In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity. Like numbers refer to like elements throughout.

It will be understood that, although the terms first, second, third etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the inventive concept.

Spatially relative terms, such as “beneath”, “below”, “lower”, “under”, “above”, “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” or “under” other elements or features would then be oriented “above” the other elements or features. Thus, the exemplary terms “below” and “under” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. In addition, it will also be understood that when a layer is referred to as being “between” two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the inventive concept. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.

It will be understood that when an element or layer is referred to as being “on”, “connected to”, “coupled to”, or “adjacent to” another element or layer, it can be directly on, connected, coupled, or adjacent the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly connected to”, “directly coupled to”, or “immediately adjacent to” another element or layer, there are no intervening elements or layers present.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this inventive concept belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and/or the present specification and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

FIG. 1 is a block diagram illustrating a nonvolatile memory device according to some embodiments of the inventive concept. Referring to FIG. 1, a nonvolatile memory device 100 may include a memory cell array 110, an address decoder 120, a read/write circuit 130, a voltage generating circuit 140, and control logic 150.

The memory cell array 110 may include a plurality of memory cell groups. For example, the memory cell array 110 may include a plurality of cell strings which are arranged on a substrate along row and column directions. Each cell string may include a plurality of memory cells stacked along a direction perpendicular to a surface of the substrate. That is, the memory cells may be provided on the substrate along rows and columns and may be stacked in a direction perpendicular to the substrate to form a three-dimensional structure. In some embodiments, each memory cell of the memory cell array 110 may store one or more bits of data.

The address decoder 120 may be coupled with the memory cell array 110 via word lines WL, string selection lines SSL, and ground selection lines GSL. The address decoder 120 may be configured to operate responsive to the control of the control logic 150. The address decoder 120 may receive an address ADDR from an external device.

The address decoder 120 may be configured to decode a row address of the input address ADDR. The address decoder 120 may be configured to select a word line corresponding to a decoded row address of the word lines WL. The address decoder 120 may be configured to select a string selection line SSL and a ground selection line GSL corresponding to the decoded row address of the string selection lines SSL and the ground selection lines GSL.

The address decoder 120 may be configured to decode a column address of the input address ADDR. The address decoder 120 may provide the decoded column address DCA to the read/write circuit 130.

In some embodiments, the address decoder 120 may include a row decoder decoding a row address, a column decoder decoding a column address, and an address buffer storing the input address ADDR.

The read/write circuit 130 may be coupled with the memory cell array 110 via bit lines BL. The read/write circuit 130 may be configured to exchange data with an external device. The read/write circuit 130 may operate responsive to the control of the control logic 150. The read/write circuit 130 may select bit lines BL in response to the decoded column address DCA provided from the address decoder 120.

In some embodiments, the read/write circuit 130 may receive data from an external device to write it in the memory cell array 110. The read/write circuit 130 may read data from the memory cell array 110 to output it to the external device. The read/write circuit 130 may read data from the first storage area of the memory cell array 110 to write it in the second storage area thereof. That is, the read/write circuit 130 may perform a copy-back operation.

In some embodiments, the read/write circuit 130 may include constituent elements such as a page buffer (or, a page register), a column selecting circuit, a data buffer, and the like. In some embodiments, the read/write circuit 130 may include constituent elements such as a sense amplifier, a write driver, a column selecting circuit, a data buffer, and the like.

The voltage generating circuit 140 may operate responsive to the control of the control logic 150. The voltage generating circuit 140 may be configured to generate various voltages for the nonvolatile memory device 100. In some embodiments, the voltage generating circuit 140 may be configured to supply an erase voltage Vers to the memory cell array 110 in response to an erase enable signal Een. The voltage generating circuit 140 may be configured to drive the ground selection lines GSL, the word lines WL, and the string selection lines SSL via the address decoder 120 in response to the erase enable signal Een.

The control logic 150 may be coupled with the address decoder 120, the read/write circuit 130, and the voltage generating circuit 140. The control logic 150 may be configured to control an overall operation of the nonvolatile memory device 100. At an erase operation, the control logic 150 may be configured to provide the erase enable signal Een to the voltage generating circuit 140.

FIG. 2 is a diagram illustrating a memory cell array in FIG. 1 according to some embodiments of the inventive concept. Referring to FIGS. 1 and 2, a memory cell array 110 may include a plurality of memory blocks BLK1 to BLKz, each of which is connected with a plurality of bit lines BL, a plurality of string selection lines SSL, a plurality of word lines WL, a ground selection line GSL, and a common source line CSL.

In some embodiments, the plurality of memory blocks BLK1 to BLKz may be selected by an address decoder 120 in FIG. 1. For example, the address decoder 120 may be configured to select a memory block corresponding to an input address ADDR among the plurality of memory blocks BLK1 to BLKz.

Each of the memory blocks BLK1 to BLKz may be formed to have a three-dimensional structure (e.g., a vertical structure). For example, each of the memory blocks BLK1 to BLKz may include structures extending along the first to third directions. Although not shown in FIG. 2, each of the memory blocks BLK1 to BLKz may include a plurality of cell strings extending along the second direction. Although not shown in FIG. 2, a plurality of cell strings may be spaced apart from one other along the first and third directions. Each cell string may be coupled with a bit line BL, a string selection line SSL, a plurality of word lines WL, a ground selection line GSL, and a common source line CSL.

FIG. 3 is a plane diagram of one of memory blocks in FIG. 1 according to some embodiments of the inventive concept. In some embodiments, a plan view illustrating conductive layers of a memory block BLKa is shown in FIG. 3. FIG. 4 is a perspective view taken along a line I-I′ of a memory block in FIG. 3 according to some embodiments of the inventive concept. FIG. 5 is a cross-sectional view taken along a line I-I′ of a memory block in FIG. 3 according to some embodiments of the inventive concept.

Referring to FIGS. 3 to 5, the memory block BLKa may include three-dimensional structures extending along the first to third directions.

A substrate 111 is provided. The substrate 111 may be a well having the first conductivity type, for example. The substrate 111 may be a p-well in which the Group III element such as boron is injected. The substrate 111 may be a pocket p-well which is provided within an n-well. Below, it is assumed that the substrate 111 is a p-well (or, a pocket p-well). However, the substrate 111 is not limited to p-type.

A plurality of doping regions 311 to 313 extending along the first direction may be provided in the substrate 111. The doping regions 311 to 313 may be spaced apart along the third direction. The doping regions 311 to 313 illustrated in FIGS. 3 to 5 may be referred to as the first to third doping regions 311 to 313, respectively.

The first to third doping regions 311 to 313 may have an n-type conductive material different from that of the substrate 111. Below, it is assumed that the first to third doping regions 311 to 313 are n-type. However, the first to third doping regions 311 to 313 are not limited to n-type and may be p-type in some embodiments.

Between adjacent doping regions of the first to third doping regions 311 to 313, a plurality of insulation materials 112 and 112 a may be provided sequentially along the second direction (i.e., a direction perpendicular to the substrate 111). The insulation materials 112 and 112 a may be formed to be spaced apart along the second direction. In some embodiments, the insulation materials 112 and 112 a may be extended along the first direction. For example, the insulation materials 112 and 112 a may include an insulation material such as silicon oxide. In some embodiments, a thickness of the insulation material 112 a contacting with the substrate 111 may be thinner than that of the insulation materials 112.

Between adjacent doping regions of the first to third doping regions 311 to 313, a plurality of pillars PL11, PL12, PL21, and PL22 may be arranged sequentially along the first direction so as to penetrate the plurality of insulation materials 112 and 112 a along the second direction. For example, the pillars PL11, PL12, PL21, and PL22 may contact with the substrate 111 through the insulation materials 112 and 112 a.

In some embodiments, the pillars PL11, PL12, PL21, and PL22 may be formed of a plurality of materials, respectively. For example, the pillars PL11, PL12, PL21, and PL22 may include channel films 114 and inner materials 115. In each of the pillars PL11, PL12, PL21, and PL22, an inner material and a channel film surrounding the inner material may be provided.

The channel films 114 may include a semiconductor material (e.g., silicon) having the first conductive type. For example, the channel films 114 may include a semiconductor material (e.g., silicon) having the same conductive type as the substrate 111. Below, it is assumed that the channel films 114 include p-type silicon. However, the channel films 114 may not be limited to include the p-type silicon. For example, the channel films 114 may include intrinsic semiconductor being a nonconductor.

The inner materials 115 may include an insulation material. For example, the inner materials 115 may include an insulation material such as silicon oxide. However, some embodiments provide that the inner materials 115 may include a void or an air gap.

Information storage films 116 may be provided between adjacent doping regions of the first to third doping regions 311 and 313 along exposed surfaces of the insulation materials 112 and 112 a and the pillars PL11, PL12, PL21, and PL22. In some embodiments, a thickness of the information storage film 116 may be less than half a distance between the insulation materials 112 and 112 a.

Between adjacent doping regions of the first to third doping regions 311 to 313, conductive materials CM1 to CM8 may be provided on exposed surfaces of the information storage films 116. For example, the conductive material CM1 to CM8 extending along the first direction may be provided between an information storage film 116 provided at a lower surface of an upper insulation material of the insulation materials 112 and 112 a and the information storage film 116 provided at an upper surface of a lower insulation material of the insulation materials 112 and 112 a.

The conductive materials CM1 to CM8 and the insulation materials 112 and 112 a may be separated on the doping regions 311 to 313 by word line cuts. In some embodiments, the conductive materials CM1 to CM8 may include a metallic conductive material. The conductive materials CM1 to CM8 may include a nonmetallic conductive material such as polysilicon.

In some embodiments, information storage films provided on an upper surface of an insulation material placed at the uppermost layer among the insulation materials 112 and 112 a can be removed. For example, information storage films provided at sides opposite to the pillars PL among sides of the insulation materials 112 and 112 a can be removed.

A plurality of drains 320 may be provided on the plurality of pillars PL11, PL12, PL21, and PL22, respectively. The drains 320 may include a semiconductor material (e.g., silicon) having the second conductivity type, for example. The drains 320 may include an n-type semiconductor material (e.g., silicon). Below, it is assumed that the drains 320 include n-type silicon. However, the present invention is not limited thereto. The drains 320 can be extended to the upside of the channel films 114 of the pillars PL11, PL12, PL21, and PL22.

Bit lines BL1 and BL2 extending in the third direction may be provided on the drains 320 so as to be spaced apart from one another along the first direction. The bit lines BL1 and BL2 may be coupled with the drains 320. In some embodiments, the drains 320 and the bit lines BL may be connected via contact plugs (not shown). The bit lines BL may include a metallic conductive material. However, some embodiments provide that the bit lines BL may include a nonmetallic conductive material such as polysilicon.

Below, rows and columns of pillars PL11, PL12, PL21, and PL22 in the memory block BLKa may be defined. In some embodiments, rows of the pillars PL11, PL12, PL21, and PL22 may be defined according to whether the conductive materials CM1 to CM8 are separated or not. The conductive materials CM1 to CM8 may be separated on the basis of the doping region 312.

Pillars PL11 and PL12 connected via the conductive materials CM1 to CM8 with the information storage films 116 provided between the first and second doping regions 311 and 312 may constitute the first row of pillars. Pillars PL21 and PL22 connected via the conductive materials CM1 to CM8 with the information storage films 116 provided between the second and third doping regions 312 and 313 may constitute the second row of pillars.

Columns of the pillars PL11, PL12, PL21, and PL22 may be defined along the bit lines BL1 and BL2. Pillars PL11 and PL21 connected with the first bit line BL1 via the drain 320 may constitute the first column of pillars. Pillars PL12 and PL22 connected with the second bit line BL2 via the drain 320 may constitute the second column of pillars.

Below, heights of the conductive materials CM1 to CM8 may be defined. The conductive materials CM1 to CM8 may have the first to eighth heights according to a distance from the substrate 111. The conductive materials CM1 closest to the substrate 111 may have the first height. The conductive materials CM8 closest to the bit lines BL1 and BL2 may have the eighth height.

Each of the pillars PL11, PL12, PL21, and PL22 may constitute one cell string with adjacent information storage films 116 and adjacent conductive materials CM1 to CM8. That is, the pillars PL11, PL12, PL21, and PL22 may constitute a plurality of cell strings with information storage films 116 and a plurality of conductive materials CM1 to CM8.

Each of cell strings may include a plurality of cell transistors CT stacked in a direction perpendicular to the substrate 111. The cell transistors CT will be more fully described with reference to FIG. 6.

FIG. 6 is a diagram illustrating one of cell transistors in FIG. 5. In some embodiments, in FIG. 6, there may be illustrated a cell transistor with the fifth height among a plurality of cell transistors CT corresponding to a pillar PL11 of the first row and the first column.

Referring to FIGS. 3 to 6, cell transistors CT may be formed of the fifth conductive material CM5, a part of a pillar PL11 adjacent the fifth conductive material CM5, and an information storage film provided between the conductive material CM5 and the pillar PL11.

The information storage films 116 may extend to upper surfaces and lower surfaces of the conductive materials CM1 to CM8 from regions between the conductive materials CM1 to CM8 and the pillars PL11, PL12, PL21, and PL22. Each of the information storage films 116 may include the first to third sub insulation films 117, 118, and 119.

In the cell transistors CT, the channel films 114 of the pillars PL11, PL12, PL21, and PL22 may include the same p-type silicon as the substrate 111. The channel films 114 may act as bodies of cell transistors CT. The channel films 114 may be formed in a direction perpendicular to the substrate 111. The channel films 114 of the pillars PL11, PL12, PL21, and PL22 may act as a vertical body. Vertical channels may be formed at the channel films 114 of the pillars PL11, PL12, PL21, and PL22.

The first sub insulation films 117 adjacent the pillars PL11, PL12, PL21, and PL22 may act as tunneling insulation films of the cell transistors CT. For example, the first sub insulation films 117 adjacent the pillars PL11, PL12, PL21, and PL22 may include a thermal oxide film, respectively. The first sub insulation films 117 may include a silicon oxide film, respectively.

The second sub insulation films 118 may act as charge storage films of the cell transistors CT. For example, the second sub insulation films 118 may act as a charge trap film, respectively. For example, the second sub insulation films 118 may include a nitride film or a metal oxide film (e.g., an aluminum oxide film, a hafnium oxide film, etc.), respectively. The second sub insulation films 118 may include a silicon nitride film.

The third sub insulation films 119 adjacent the conductive materials CM1 to CM8 may act as blocking insulation films of the cell transistors CT. In some embodiments, the third sub insulation films 119 may be formed of a single layer or multiple layers. The third sub insulation films 119 may be a high dielectric film (e.g., an aluminum oxide film, a hafnium oxide film, etc.) having a dielectric constant larger than those of the first and second sub insulation films 117 and 118. The third sub insulation films 119 may include a silicon oxide film, respectively.

In some embodiments, the first to third sub insulation films 117 to 119 may constitute ONO (oxide-nitride-oxide).

The plurality of conductive materials CM1 to CM8 may act as a gate (or, a control gate), respectively.

That is, the plurality of conductive materials CM1 to CM8 acting as gates (or, control gates), the third sub insulation films 119 acting as block insulation films, the second sub insulation films 118 acting as charge storage films, the first sub insulation films 117 acting as tunneling insulation films, and the channel films 114 acting as vertical bodies may constitute cell transistors CT stacked in a direction perpendicular to the substrate 111. Some embodiments provide that the cell transistors CT may be a charge trap type cell transistor.

The cell transistors CT can be used for different purposes according to height. For example, among the cell transistors CT, at least one cell transistor placed at an upper portion may be used as a string selection transistor. Among the cell transistors CT, at least one cell transistor placed at a lower portion may be used as a ground selection transistor. Remaining cell transistors may be used as a memory cell and a dummy memory cell.

The conductive materials CM1 to CM8 may extend along a row direction (the first direction) to be connected with a plurality of pillars PL11 and PL12 or PL21 and PL22. The conductive materials CM1 to CM8 may constitute conductive lines interconnecting cell transistors CT of the pillars PL11 and PL12 or PL21 and PL22 in the same row.

In some embodiments, the conductive materials CM1 to CM8 may be used as a string selection line, a ground selection line, a word line, or a dummy word line according to the height.

FIG. 7 is a circuit diagram illustrating an equivalent circuit of a memory block described in FIGS. 3 to 6. Referring to FIGS. 3 to 7, cell strings CS11 and CS21 may be connected between the first bit line BL1 and a common source line CSL, and cell strings CS12 and CS22 may be connected between the second bit line BL2 and the common source line CSL. The cell strings CS11, CS21, CS12, and CS22 may correspond to pillars PL11, PL21, PL12, and PL22, respectively.

The pillar PL11 of the first row and the first column may form the cell string CS11 of the first row and the first column with conductive materials CM1 to CM8 and information storage films 116. The pillar PL12 of the first row and the second column may form the cell string CS12 of the first row and the second column with the conductive materials CM1 to CM8 and the information storage films 116. The pillar PL21 of the second row and the first column may form the cell string CS21 of the second row and the first column with the conductive materials CM1 to CM8 and the information storage films 116. The pillar PL22 of the second row and the second column may form the cell string CS22 of the second row and the second column with the conductive materials CM1 to CM8 and the information storage films 116.

In the cell strings CS11, CS21, CS12, and CS22, cell transistors with the first height may act as ground selection transistors GST. Cell strings of the same row may share a ground selection line GSL. Cell strings of different rows may share the ground selection line GSL. In some embodiments, the first conductive materials CM1 may be interconnected to form the ground selection line GSL.

In the cell strings CS11, CS21, CS12, and CS22, cell transistors with the second to sixth heights may act as the first to sixth memory cells MC1 to MC6. The first to sixth memory cells MC1 to MC6 may be connected with the first to sixth word lines WL1 to WL6, respectively. Memory cells having the same height and corresponding to the same row may share a word line. Memory cells having the same height and corresponding to different rows may share a word line. That is, memory cells MC having the same height may share a word line.

In some embodiments, the second conductive materials CM2 may be interconnected to form the first word line WL1. The third conductive materials CM3 may be interconnected to form the second word line WL2. The fourth conductive materials CM4 may be interconnected to form the third word line WL3. The fifth conductive materials CM5 may be interconnected to form the fourth word line WL4. The sixth conductive materials CM6 may be interconnected to form the fifth word line WL5. The seventh conductive materials CM7 may be interconnected to form the sixth word line WL6.

In the cell strings CS11, CS21, CS12, and CS22, cell transistors with the eighth height may act as string selection transistors SST. The string selection transistors SST may be connected with the first and second string selection lines SSL1 and SSL2. Cell strings of the same row may share a string selection line SSL. Cell strings of different rows may be connected with different string selection lines. In some embodiments, each of the first and second string selection lines SSL1 and SSL2 may correspond to the eight conductive materials CM8. That is, the pillars PL11, PL12, PL21, and PL22, that is, rows of cell strings CS11, CS12, CS21, and CS22 may be defined by the first and second string selection lines SSL1 and SSL2.

Below, string selection transistors connected with the first string selection line SSL1 may be referred to as the first string selection transistors SST1, and string selection transistors connected with the second string selection line SSL2 may be referred to as the second string selection transistors SST2.

A common source line CSL may be connected in common with the cell strings CS11, CS12, CS21, and CS22. For example, the first to third doping regions 311 to 313 may be interconnected to form the common source line CSL.

As illustrated in FIG. 7, memory cells having the same height may be connected in common with one word line. Accordingly, when a word line with a specific height is selected, all cell strings CS11, CS12, CS21, and CS22 connected with the selected word line may be selected.

Cell strings of different rows may be connected with different string selection lines. Accordingly, in the cell strings CS11, CS12, CS21, and CS22 connected with the same word line, an unselected row of cell strings CS11 and CS12 or CS21 and CS22 may be electrically separated from the bit lines BL1 and BL2 by selecting and unselecting the first and second string selection lines SSL1 and SSL2. A selected row of cell strings CS21 and CS22 or CS11 and CS12 may be electrically connected with the bit lines BL1 and BL2.

That is, rows of the cell strings CS11, CS 12, CS21, and CS22 may be selected by selecting and unselecting the first and second string selection lines SSL1 and SSL2. Columns of cell strings in a selected row may be selected by selecting the bit lines BL1 and BL2.

In some embodiments, at least one of the word lines WL1 to WL6 may be used as a dummy word line. For example, a word line adjacent the string selection lines SSL1 and SSL2, a word line adjacent the ground selection line GSL, or at least one of word lines between the string selection lines SSL1 and SSL2 and the ground selection line GSL may be used as a dummy word line.

In some embodiments, at least two conductive materials of the conductive materials CM1 to CM8 may form string selection lines. For example, the seventh and eighth conductive materials CM7 and CM8 may be used as string selection lines. At this time, the seventh and eighth conductive materials CM7 and CM8 in the same row may be connected in common.

In some embodiments, at least two conductive materials of the conductive materials CM1 to CM8 may form a ground selection line. For example, the first and second conductive materials CM1 and CM2 may be used as a ground selection line. At this time, the first and second conductive materials CM1 and CM2 in the same row may be connected in common.

In some embodiments, the first conductive materials CM1 may form two ground selection lines being electrically separated.

FIG. 8 is a diagram illustrating a voltage condition of a nonvolatile memory device in FIG. 1 at an erase operation. In some embodiments, an erase operation may be executed by the memory block. Below, an erase operation will be described with reference to a memory block BLKa described in FIGS. 3 to 7.

At an erase operation, string selection lines SSL1 and SSL2 may be floated, and a word line erase voltage Vwe may be applied to word line WL1 to WL6. For example, the word line erase voltage Vwe may be a ground voltage Vss. A ground selection line GSL may be floated, and an erase voltage Vers may be supplied to a substrate 111.

The substrate 111 may have the same conductivity as channel films 114. Accordingly, the erase voltage Vers applied to the substrate 111 may be transferred to the channel films 114. In some embodiments, the erase voltage Vers may be a high voltage.

The ground and string selection lines GSL, SSL1, and SSL2 may be floated. Accordingly, when voltages of the channel films 114 vary, the ground and string selection lines GSL, SSL1, and SSL2 may suffer from the coupling. That is, when voltages of the channel films 114 are increased to the erase voltage Vers, voltages of the ground and string selection lines GSL, SSL1, and SSL2 may also increase. Accordingly, ground and string selection transistors GST, SST1, and SST2 may be erase inhibited.

The word line erase voltage Vwe may be applied to the word lines WL1 to WL6. In some embodiments, the word line erase voltage Vwe may be a low voltage. For example, the word line erase voltage Vwe may be a ground voltage Vss. The Fowler-Nordheim tunneling may be generated at memory cells MC1 to MC6 due to a voltage difference between the channel films 114 and the word lines WL1 to WL6. This means that the memory cells MC1 to MC6 are erased.

If the ground selection line GSL is at a floating state, the ground selection transistors GST may have a quasi-on state. That is, when the erase voltage Vers is applied to the substrate 111, channels may be formed partially at the channel films 114 corresponding to the ground selection transistors GST. In FIG. 9, there is illustrated a cross-section view taken along a line I-I′ when channels of the ground selection transistors GST are formed.

Referring to FIG. 9, the substrate 111 and the channel films 114 may be p-type, while channels IC formed at the ground selection transistors GST may be n-type. Accordingly, the erase voltage Vers supplied to the substrate 111 may be shut off by the ground selection transistors GST. This means that the erase voltage Vers is not transferred to the channel films 114 corresponding to the memory cells MC1 to MC6.

At this time, the memory cells MC1 to MC6 may not be erased. Further, the gate induced drain leakage (GIDL) may be generated between the ground selection transistors GST and the memory cells MC1. This may be caused by a voltage difference between the channel films 114 corresponding to the memory cells MC1 to MC6 and the substrate 111. The ground selection transistors GST may be programmed due to the GIDL.

As another example, before a voltage of the substrate 111 is transferred to the channel films 114 corresponding to the ground selection line GSL, a voltage of the ground selection line GSL can be increased due to the coupling. At this time, channels IC of the ground selection transistors GST may be formed by a voltage of the ground selection line GSL. In this case, no memory cells MC1 to MC6 may be erased, and the ground selection transistors GST may be programmed due to the GIDL.

As loading of the ground selection line GSL increases, a rising degree of a voltage of the ground selection line GSL may decrease due to the coupling from the substrate 111 and the channel films 114. If a voltage of the ground selection line GSL decreases, the ground selection transistors GST may be erased due to a voltage difference between a voltage of the ground selection line GSL and voltages of the channel films 114.

If the ground selection line GSL is floated at the erase operation, the ground selection transistors GST may be programmed or erased. Likewise, string selection transistors SST1 and SST2 may experience this phenomenon. That is, if the string selection transistors SST1 and SST2 are floated at the erase operation, they may be programmed or erased.

With erase methods according to the inventive concept, the above-described phenomenon may be prevented by controlling the ground selection line GSL. Further, the string selection lines SSL1 and SSL2 may be controlled according to the erase method of the inventive concept.

The inventive concept will be described using embodiments where ground and string selection lines GSL, SSL1, and SSL2 are controlled at an erase operation. However, the inventive concept is not limited thereto. For example, some embodiments may be applicable to a technique where a ground selection line GSL is only controlled or a technique where string selection lines SSL1 and SSL2 are only controlled.

FIG. 10 is a flowchart illustrating erase methods according to some embodiments of the inventive concept. Referring to FIGS. 1, 3 to 7, and 10, in operation 1110, a ground voltage Vss may be applied to ground and string selection lines GSL, SSL1, and SSL2. In operation 1120, a word line erase voltage Vwe may be applied to word lines WL1 to WL6. In operation 1130, an erase voltage Vers may be applied to a substrate 111. In operation 1140, a voltage of the ground selection line GSL may be controlled according to applying of the erase voltage Vers. In operation 1150, voltages of the string selection lines SSL1 and SSL2 may be controlled according to the applying of the erase voltage Vers.

In some embodiments, loading (e.g., RC loading) of the ground selection line GSL may be smaller than that of the substrate 111. Although a voltage is simultaneously applied to the ground selection line GSL and the substrate 111, a voltage of the ground selection line GSL may increase more rapidly than that of the substrate 111. If a voltage of the ground selection line GSL becomes higher by a predetermined level than a voltage of the substrate 111, the Fowler-Nordheim tunneling may occur at the ground selection transistors GST. That is, the ground selection transistors GST may be programmed. Likewise, the string selection transistors SST1 and SST2 may experience this phenomenon. That is, the string selection transistors SST1 and SST2 may be programmed.

The erase method according to some embodiments of the inventive concept may include controlling the ground and string selection lines GSL, SSL1, and SSL2 such that the ground and string selection transistors GST, SST1, and SST2 are not programmed and erased and don't fall into quasi-on and/or turn-on states. In some embodiments, a voltage difference between the substrate 111 and the ground and string selection lines GSL, SSL1, and SSL2 may be kept within a predetermined/specific range. For example, voltages of the ground and string selection lines GSL, SSL1, and SSL2 may be controlled within a predetermined range on the basis of half a voltage of the substrate 111.

FIG. 11 is a flowchart for describing operations of controlling voltages of ground and string selection lines according to some embodiments of the inventive concept. Referring to FIGS. 1, 3 to 7, and 11, in operation 1210, the first ground selection line voltage VGSL1 may be applied to a ground selection line GSL. A rising slope of the first ground selection line voltage VGSL1 may be slower than that of a substrate voltage.

In operation 1220, the first string selection line voltage VSSL1 may be applied to string selection lines SSL1 and SSL2. A rising slope of the first string selection line voltage VSSL1 may be slower than that of a substrate voltage.

FIG. 12 is a diagram illustrating voltage variations according to an erase method of the inventive concept. Referring to FIG. 12, at t1, the first string selection line voltage VSSL1 may be applied to string selection lines SSL1 and SSL2. A word line erase voltage Vwe may be applied to word lines WL1 to WL6. The first ground selection line voltage VGSL1 may be applied to a ground selection line GSL, and an erase voltage Vers may be applied to a substrate 111.

In some embodiments, voltages of the string selection lines SSL1 and SSL2 may be controlled such that a rising slope of voltages of the string selection lines SSL1 and SSL2 is slower than that of the substrate 111.

A rising slope of voltages of the string selection lines SSL1 and SSL2 may be controlled such that string selection transistors SST1 and SST2 are not programmed. For example, a rising slope of voltages of the string selection lines SSL1 and SSL2 may be controlled such that voltages of the string selection lines SSL1 and SSL2 are lower than a voltage of the substrate 111.

A rising slope of voltages of the string selection lines SSL1 and SSL2 may be controlled such that the string selection transistors SST1 and SST2 are not erased. For example, a rising slope of voltages of the string selection lines SSL1 and SSL2 may be controlled such that voltages of the string selection lines SSL1 and SSL2 don't become lower by a specific level than a voltage of the substrate 111.

A rising slope of voltages of the string selection lines SSL1 and SSL2 may be controlled such that the string selection transistors SST1 and SST2 don't fall into a quasi-on or turn-on state.

A voltage of the ground selection line GSL may be controlled such that a rising slope of a voltage of the ground selection line GSL is slower than that of the substrate 111.

A rising slope of a voltage of the ground selection line GSL may be controlled such that ground selection transistors GST are not programmed. For example, a rising slope of a voltage of the ground selection line GSL may be controlled such that a voltage of the ground selection line GSL is lower than a voltage of the substrate 111.

A rising slope of a voltage of the ground selection line GSL may be controlled such that the ground selection transistors GST are not erased. For example, a rising slope of a voltage of the ground selection line GSL may be controlled such that a voltage of the ground selection line GSL does not become lower by a specific level than a voltage of the substrate 111.

A rising slope of a voltage of the ground selection line GSL may be controlled such that the ground selection transistors GST don't fall into a quasi-on or turn-on state.

At t3, voltages of the string selection lines SSL1 and SSL2 may reach the first string selection line voltage VSSL1, a voltage of the ground selection line GSL may reach the first ground selection line voltage VGSL1, and a voltage of the substrate 111 may reach an erase voltage Vers. In some embodiments, the first string selection line voltage VSSL1 may be controlled such that the string selection transistors SST1 and SST2 are not erased due to a voltage difference between the first string selection line voltage VSSL1 and the erase voltage Vers. For example, the first string selection line voltage VSSL1 may be controlled to have a level within a specific range on the basis of half an erase voltage Vers.

The first ground selection line voltage VGSL1 may be controlled such that the ground selection transistors GST are not erased due to a voltage difference between the first ground selection line voltage VGSL1 and the erase voltage Vers. For example, the first ground selection line voltage VGSL1 may be controlled to have a level within a specific range on the basis of half an erase voltage Vers.

Memory cells MC1 to MC6 may be erased by a voltage difference between the word line erase voltage. Vwe and the erase voltage Vers.

At t4, voltages of the string selection lines SSL1 and SSL2 may start to decrease from the first string selection line voltage VSSL1. A voltage of the ground selection line GSL may start to decrease from the first ground selection line voltage VGSL1. A voltage of the substrate 111 may start to decrease from the erase voltage Vers.

At t5, voltages of the string and ground selection lines SSL1, SSL2, and GSL and the substrate may be lowered to a ground voltage VSS.

In some embodiments, voltages of the string selection lines SSL1 and SSL2 may be controlled such that a falling slope of voltages of the string selection lines SSL1 and SSL2 may be slower than that of the substrate 111.

A falling slope of voltages of the string selection lines SSL1 and SSL2 may be controlled such that the string selection transistors SST1 and SST2 are not programmed. For example, a falling slope of voltages of the string selection lines SSL1 and SSL2 may be controlled such that voltages of the string selection lines SSL1 and SSL2 are lower than a voltage of the substrate 111.

A falling slope of voltages of the string selection lines SSL1 and SSL2 may be controlled such that the string selection transistors SST1 and SST2 are not erased. For example, a falling slope of voltages of the string selection lines SSL1 and SSL2 may be controlled such that voltages of the string selection lines SSL1 and SSL2 don't become lower by a specific level than a voltage of the substrate 111.

A falling slope of voltages of the string selection lines SSL1 and SSL2 may be controlled such that the string selection transistors SST1 and SST2 don't fall into a quasi-on or turn-on state.

The voltage of the ground selection line GSL may be controlled such that a falling slope of a voltage of the ground selection line GSL is slower than that of the substrate 111.

A falling slope of a voltage of the ground selection line GSL may be controlled such that the ground selection transistors GST are not programmed. For example, a falling slope of a voltage of the ground selection line GSL may be controlled such that a voltage of the ground selection line. GSL is lower than a voltage of the substrate 111.

A falling slope of a voltage of the ground selection line GSL may be controlled such that the ground selection transistors GST are not erased. For example, a falling slope of a voltage of the ground selection line GSL may be controlled such that a voltage of the ground selection line GSL does not become lower by a specific level than a voltage of the substrate 111.

A falling slope of a voltage of the ground selection line GSL may be controlled such that the ground selection transistors GST don't fall into a quasi-on or turn-on state.

As described above, rising and falling slopes of a voltage of the ground selection line GSL may be controlled to be slower than those of the substrate 111, based upon applying of the erase voltage Vers to the substrate 111. A voltage difference between voltages of the ground selection line GSL and the substrate 111 may be kept within a specific range.

For example, a voltage of the ground selection line GSL may be prevented from being increased over a voltage of the substrate 111. Accordingly, programming of the ground selection transistors GST may be prevented. Further, a voltage of the ground selection line GSL may be prevented from becoming lower by a specific voltage other than a voltage of the substrate 111. Accordingly, erasing of the ground selection transistors GST may be prevented. Further, it is possible to prevent the ground selection transistors GST from falling into a quasi-on or turn-on state before a voltage of the substrate 111 is transferred to the channel films 114. Accordingly, programming of deterioration of the ground selection transistors GST due to the GIDL may be prevented.

Likewise, rising and falling slopes of voltages of the string selection lines SSL1 and SSL2 may be controlled to be slower than those of the substrate 111, based upon applying of the erase voltage Vers to the substrate 111. A voltage difference between voltages of the string selection lines SSL1 and SSL2 and the substrate 111 may be kept within a specific range.

For example, voltages of the string selection lines SSL1 and SSL2 may be prevented from being increased over a voltage of the substrate 111. Accordingly, programming of the string selection transistors SST1 and SST2 may be prevented. Further, voltages of the string selection lines SSL1 and SSL2 may be prevented from becoming lower by a specific voltage other than a voltage of the substrate 111. Accordingly, erasing of the string selection transistors SST1 and SST2 may be prevented. Further, it is possible to prevent the string selection transistors SST1 and SST2 from falling into a quasi-on or turn-on state before a voltage of the substrate 111 is transferred to the channel films 114. Accordingly, programming of deterioration of the string selection transistors SST1 and SST2 due to the GIDL may be prevented.

FIG. 13 is a block diagram illustrating a nonvolatile memory device according to some embodiments of the inventive concept. Referring to FIG. 13, a nonvolatile memory device 100 a may include a memory cell array 110, an address decoder 120, a read/write circuit 130, a voltage generating circuit 140 a, and control logic 150.

The nonvolatile memory device 100 a may be substantially identical to that in FIG. 1 except for the voltage generating circuit 140 a. As such, additional discussion of previously described aspects of the memory device 100 a is thus omitted.

The voltage generating circuit 140 a may be configured to generate various voltages for the nonvolatile memory device 100 a. In some embodiments, the voltage generating circuit 140 a may be configured to supply an erase voltage Vers to the memory cell array 110 in response to an erase enable signal Een. The voltage generating circuit 140 a may be configured to control voltage of ground selection lines GSL, word lines WL, and string selection lines SSL via the address decoder 120 in response to applying of the erase voltage Vers.

The voltage generating circuit 140 a may include a delay 141, which may include a delay circuit and/or a delay function. The delay 141 may generate an internal signal after the erase enable signal Een is received and a delay time elapses. The voltage generating circuit 140 a may drive the ground selection lines GSL, the word lines WL, and the string selection lines SSL via the address decoder 120 in response to the internal signal. That is, the voltage generating circuit 140 a may control voltages of the ground selection lines GSL, the word lines WL, and the string selection lines SSL via the address decoder 120 after the erase voltage Vers is applied and the delay time elapses.

FIG. 14 is a flowchart for describing operations of controlling voltages of ground and string selection lines according to another exemplary embodiment of the inventive concept. Referring to FIGS. 3 to 7, 11, 13, and 14, in operation 1310, the second ground selection line voltage VGSL2 may be applied to a ground selection line GSL after a delay time. In operation 1320, the second string selection line voltage VSSL2 may be applied after a delay time DT. The delay time DT may be a-time determined by a delay 141.

FIG. 15 is a diagram illustrating voltage variations according to erase methods described in FIGS. 10 to 14. Referring to FIGS. 3 to 7, 10, and 13 to 15, at t1, a word line erase voltage Vwe may be applied to word lines WL1 to WL6. An erase voltage Vers may be applied to a substrate 111. String and ground selection lines SSL1, SSL2, and GSL may be grounded.

After the delay time DT, that is, at t2, the second string selection line voltage VSSL2 may be applied to string selection lines SSL1 and SSL2. The second ground selection line voltage VGSL2 may be applied to the ground selection line GSL.

The delay time DT may be controlled such that string selection transistors SST1 and SST2 are not programmed. For example, the delay time DT may be controlled such that voltages of the string selection lines SSL1 and SSL2 are lower than a voltage of the substrate 111.

The delay time DT may be controlled such that string selection transistors SST1 and SST2 are not erased. For example, the delay time DT may be controlled such that voltages of the string selection lines SSL1 and SSL2 don't become lower by a specific level than a voltage of the substrate 111.

The delay time DT may be controlled such that the string selection transistors SST1 and SST2 don't fall into a quasi-on or turn-on state.

The delay time DT may be controlled such that ground selection transistors GST are not programmed. For example, the delay time DT may be controlled such that a voltage of the ground selection line GSL is lower than a voltage of the substrate 111.

The delay time DT may be controlled such that ground selection transistors GST are not erased. For example, the delay time DT may be controlled such that a voltage of the ground selection line GSL does not become lower by a specific level than a voltage of the substrate 111.

The delay time DT may be controlled such that the ground selection transistors GST don't fall into a quasi-on or turn-on state.

At t3, voltages of the string selection lines SSL1 and SSL2 may reach the second string selection line voltage VSSL2, a voltage of the ground selection line GSL may reach the second ground selection line voltage VGSL2, and a voltage of the substrate 111 may reach an erase voltage Vers.

The second string selection line voltage VSSL2 may be controlled such that the string selection transistors SST1 and SST2 are not erased due to a voltage difference between the string selection lines SSL1 and SSL2 and the substrate 111. For example, the second string selection line voltage VSSL2 may be controlled to have a level within a specific range on the basis of half an erase voltage Vers.

The second ground selection line voltage VGSL2 may be controlled such that the ground selection transistors GST are not erased due to a voltage difference between the ground selection line GSL and the substrate 111. For example, the second ground selection line voltage VGSL2 may be controlled to have a level within a specific range on the basis of half an erase voltage Vers.

Memory cells MC1 to MC6 may be erased by a voltage difference between the word lines WL1 to WL6 and the substrate 111.

At t4, voltages of the string selection lines SSL1 and SSL2 may start to decrease from the second string selection line voltage VSSL2. A voltage of the ground selection line GSL may start to decrease from the second ground selection line voltage VGSL2. A voltage of the substrate 111 may start to decrease from the erase voltage Vers.

After voltages of the string and ground selection lines SSL1, SSL2, and GSL are lowered to a ground voltage VSS, at t5, a voltage of the substrate 111 may be lowered to the ground voltage VSS.

As described above, after the erase voltage Vers is applied to the substrate 111 and a delay time DT elapses, the second string selection line voltage VSSL2 may be supplied to the string selection lines SSL1 and SSL2. A voltage difference between the string selection lines SSL1 and SSL2 and the substrate 111 may be kept within a specific range.

For example, voltages of the string selection lines SSL1 and SSL2 may be prevented from being increased over a voltage of the substrate 111. Accordingly, programming of the string selection transistors SST1 and SST2 may be prevented. Further, voltages of the string selection lines SSL1 and SSL2 may be prevented from becoming lower than a voltage of the substrate 111 by a specific voltage. Accordingly, erasing of the string selection transistors SST1 and SST2 may be prevented. Further, it is possible to prevent the string selection lines SSL1 and SSL2 from falling into a quasi-on or turn-on state before a voltage of the substrate 111 is transferred to the channel films 114. Accordingly, programming of deterioration of the string selection lines SSL1 and SSL2 due to the GIDL may be prevented.

Likewise, after the erase voltage Vers is applied to the substrate 111 and a delay time DT elapses, the second ground selection line voltage VGSL2 may be supplied to the ground selection line GSL. A voltage difference between the ground selection line GSL and the substrate 111 may be kept within a specific range.

For example, a voltage of the ground selection line GSL may be prevented from being increased over a voltage of the substrate 111. Accordingly, programming of the ground selection transistors GST may be prevented. Further, voltages of the ground selection line GSL may be prevented from becoming lower by a specific voltage other than a voltage of the substrate 111. Accordingly, erasing of the ground selection transistors GST may be prevented. Further, it is possible to prevent the ground selection transistors GST from falling into a quasi-on or turn-on state before a voltage of the substrate 111 is transferred to the channel films 114. Accordingly, programming of deterioration of the ground selection transistors GST due to the GIDL may be prevented.

FIG. 16 is a block diagram illustrating a voltage generating circuit in FIG. 13. Referring to FIGS. 13 and 16, a voltage generating circuit 140 a may include a delay circuit 141, an erase voltage generator 142, a ground selection line driver 143, and a string selection line driver 144.

The delay circuit 141 and the erase voltage generator 142 may be configured to receive an erase enable signal Een. The delay circuit 141 may be configured to activate an internal signal IS after the erase enable signal Een is input and a delay time DT elapses.

The erase voltage generator 142 may be configured to generate an erase voltage Vers in response to the erase enable signal Een. The erase voltage Vers may be supplied to a substrate 111 of a memory cell array 110.

The ground selection line driver 143 may be configured to generate the second ground selection line voltage VGSL2 in response to the internal signal IS. The second ground selection line voltage VGSL2 may be supplied to a ground selection line GSL of a selected memory block BLKa via an address decoder 120.

The string selection line driver 144 may be configured to generate the second string selection line voltage VSSL2 in response to the internal signal IS. The second string selection line voltage VSSL2 may be supplied to string selection lines SSL1 and SSL2 of a selected memory block BLKa via the address decoder 120.

FIG. 17 is a flowchart for describing operations of controlling voltages of ground and string selection lines according to still another embodiment of the inventive concept. Referring to FIGS. 3 to 7, 10, 13, and 16, in operation 1410, a ground selection line GSL may be floated after a delay time DT. Although represented by the same symbol, the DT of FIG. 17 may or may not be the same as the DT discussed above regarding FIG. 15. In some embodiments, after generating an erase voltage Vers in response to an erase enable signal Een, a voltage generating circuit 140 a may float a ground selection line GSL if a delay time DT elapses.

In operation 1420, string selection lines SSL1 and SSL2 may be floated after the delay time DT. In some embodiments, after generating an erase voltage Vers in response to an erase enable signal Een, the voltage generating circuit 140 a may float the string selection lines SSL1 and SSL2 if the delay time DT elapses.

FIG. 18 is a diagram illustrating voltage variations according to an erase method described in FIGS. 10 to 17. Referring to FIGS. 3 to 7, 10, 13, 17, and 18, at t1, a word line erase voltage Vwe may be applied to word lines WL1 to WL6. An erase voltage Vers may be applied to a substrate 111. String and ground selection lines SSL1, SSL2, and GSL may be grounded.

After the delay time DT, that is, at t2, string selection lines SSL1 and SSL2 may be floated. A ground selection line GSL may be floated.

The delay time DT may be controlled such that string selection transistors SST1 and SST2 are not programmed. For example, the delay time DT may be controlled such that voltages of the string selection lines SSL1 and SSL2 are lower than a voltage of the substrate 111.

The delay time DT may be controlled such that string selection transistors SST1 and SST2 are not erased. For example, the delay time DT may be controlled such that voltages of the string selection lines SSL1 and SSL2 don't become lower by a specific level than a voltage of the substrate 111.

The delay time DT may be controlled such that the string selection transistors SST1 and SST2 don't fall into a quasi-on or turn-on state.

The delay time DT may be controlled such that ground selection transistors GST are not programmed. For example, the delay time DT may be controlled such that a voltage of the ground selection line GSL is lower than a voltage of the substrate 111.

The delay time DT may be controlled such that ground selection transistors GST are not erased. For example, the delay time DT may be controlled such that a voltage of the ground selection line GSL does not become lower by a specific level than a voltage of the substrate 111.

The delay time DT may be controlled such that the ground selection transistors GST don't fall into a quasi-on or turn-on state.

At t3, voltages of the string selection lines SSL1 and SSL2 may reach the first string selection line voltage VSF1, a voltage of the ground selection line GSL may reach the first ground selection line voltage VGF1, and a voltage of the substrate 111 may reach an erase voltage Vers.

The delay time DT may be controlled such that the string selection transistors SST1 and SST2 are not erased due to a voltage difference between the string selection lines SSL1 and SSL2 and the substrate 111. For example, the delay time DT may be controlled such that the first string selection line voltage VSF1 has a level within a specific range on the basis of half an erase voltage Vers. The delay time DT can be controlled according to a voltage rising slope of the string selection lines SSL1 and SSL2 by the coupling effect.

The delay time DT may be controlled such that the ground selection transistors GST are not erased due to a voltage difference between the ground selection line GSL and the substrate 111. For example, the delay time DT may be controlled such that the first ground selection line voltage VGF1 has a level within a specific range on the basis of half an erase voltage Vers. The delay time DT can be controlled according to a voltage rising slope of the ground selection line GSL by the coupling effect.

Memory cells MC1 to MC6 may be erased by a voltage difference between the word lines WL1 to WL6 and the substrate 111.

At t4, voltages of the string selection lines SSL1 and SSL2 may start to decrease from the first string selection line voltage VSF1. A voltage of the ground selection line GSL may start to decrease from the first ground selection line voltage VGF1. A voltage of the substrate 111 may start to decrease from the erase voltage Vers.

After voltages of the string and ground selection lines SSL1, SSL2, and GSL are lowered to a ground voltage VSS, at t5, a voltage of the substrate 111 may be lowered to the ground voltage VSS.

As described above, after the erase voltage Vers is applied to the substrate 111 and a delay time DT elapses, the string selection lines SSL1 and SSL2 may be floated. A voltage difference between the string selection lines SSL1 and SSL2 and the substrate 111 may be kept within a specific range.

For example, voltages of the string selection lines SSL1 and SSL2 may be prevented from being increased over a voltage of the substrate 111. Accordingly, programming of the string selection transistors SST1 and SST2 may be prevented. Further, voltages of the string selection lines SSL1 and SSL2 may be prevented from becoming lower by a specific voltage other than a voltage of the substrate 111. Accordingly, erasing of the string selection transistors SST1 and SST2 may be prevented. Further, it is possible to prevent the string selection lines SSL1 and SSL2 from falling into a quasi-on or turn-on state before a voltage of the substrate 111 is transferred to the channel films 114. Accordingly, programming of deterioration of the string selection lines SSL1 and SSL2 due to the GIDL may be prevented.

Likewise, after the erase voltage Vers is applied to the substrate 111 and a delay time DT elapses, the ground selection line GSL may be floated. A voltage difference between the ground selection line GSL and the substrate 111 may be kept within a specific range.

For example, a voltage of the ground selection line GSL may be prevented from being increased over a voltage of the substrate 111. Accordingly, programming of the ground selection transistors GST may be prevented. Further, voltages of the ground selection line GSL may be prevented from becoming lower by a specific voltage other than a voltage of the substrate 111. Accordingly, erasing of the ground selection transistors GST may be prevented. Further, it is possible to prevent the ground selection transistors GST from falling into a quasi-on or turn-on state before a voltage of the substrate 111 is transferred to the channel films 114. Accordingly, programming of deterioration of the ground selection transistors GST due to the GIDL may be prevented.

A voltage generating circuit 140 a may be substantially identical to that described with reference to FIG. 16 except that the ground and string selection lines GSL, SSL1, and SSL2 are floated according to the internal signal IS.

FIG. 19 is a block diagram illustrating a nonvolatile memory device according to some embodiments of the inventive concept. Referring to FIG. 19, a nonvolatile memory device 100 b may include a memory cell array 110, an address decoder 120, a read/write circuit 130, a voltage generating circuit 140 b, control logic 150, and a substrate monitor circuit 160.

The nonvolatile memory device 100 b may be substantially identical to that in FIG. 1 except for the voltage generating circuit 140 b and the substrate monitor circuit 160. As such, additional discussion of previously described aspects of the memory device 100 b is thus omitted.

The voltage generating circuit 140 a may be configured to supply an erase voltage Vers to the memory cell array 110 in response to an erase enable signal Een. The voltage generating circuit 140 b may be configured to control voltages of ground selection lines GSL, word lines WL, and string selection lines SSL via the address decoder 120 in response to a selection signal SE.

The substrate monitor circuit 160 may be configured to monitor a voltage of a substrate 111 of the memory cell array 110. If a voltage of the substrate 111 reaches a level of a target voltage Vtar, the substrate monitor circuit 160 may activate the selection signal SE.

FIG. 20 is a flowchart for describing operations of controlling voltages of ground and string selection lines according to some embodiments of the inventive concept. Referring to FIGS. 3 to 7, 10, 19, and 20, in operation 1510, when a voltage of a substrate 111 reaches a target voltage Vtar, the third ground selection line voltage VGSL3 may be applied to a ground selection line GSL. In operation 1520, when a voltage of the substrate 111 reaches the target voltage Vtar, the third string selection line voltage VSSL3 may be applied to string selection lines SSL1 and SSL2.

FIG. 21 is a diagram illustrating voltage variations according to erase methods described in FIGS. 10 and 20. Referring to FIGS. 3 to 7, 10, and 19 to 21, at t1, a word line erase voltage Vwe may be applied to word lines WL1 to WL6. An erase voltage Vers may be applied to a substrate 111. String and ground selection lines SSL1, SSL2, and GSL may be grounded.

At t2, a voltage of the substrate 111 may reach the target voltage Vtar. At this time, a substrate monitor circuit 160 may activate a selection signal SE. A voltage generating circuit 140 b may supply the third string selection line voltage VSSL3 to the string selection lines SSL1 and SSL2 via an address decoder 120 in response to the selection signal SE. Further, the voltage generating circuit 140 b may supply the third ground selection line voltage VGSL3 to the ground selection line GSL.

The third ground selection line voltage VGSL3 and the target voltage Vtar may be controlled such that string selection transistors SST1 and SST2 are not programmed. For example, the third ground selection line voltage VGSL3 and the target voltage Vtar may be controlled such that voltages of the string selection lines SSL1 and SSL2 are lower than a voltage of the substrate 111.

The third ground selection line voltage VGSL3 and the target voltage Vtar may be controlled such that string selection transistors SST1 and SST2 are not erased. For example, the third ground selection line voltage VGSL3 and the target voltage Vtar may be controlled such that voltages of the string selection lines SSL1 and SSL2 don't become lower by a specific level than a voltage of the substrate 111.

The third ground selection line voltage VGSL3 and the target voltage Vtar may be controlled such that the string selection transistors SST1 and SST2 don't fall into a quasi-on or turn-on state.

The third ground selection line voltage VGSL3 and the target voltage Vtar may be controlled such that ground selection transistors GST are not programmed. For example, the third ground selection line voltage VGSL3 and the target voltage Vtar may be controlled such that a voltage of the ground selection line GSL is lower than a voltage of the substrate 111.

The third ground selection line voltage VGSL3 and the target voltage Vtar may be controlled such that ground selection transistors GST are not erased. For example, the third ground selection line voltage VGSL3 and the target voltage Vtar may be controlled such that a voltage of the ground selection line GSL does not become lower by a specific level than a voltage of the substrate 111.

The third ground selection line voltage VGSL3 and the target voltage Vtar may be controlled such that the ground selection transistors GST don't fall into a quasi-on or turn-on state.

At t3, voltages of the string selection lines SSL1 and SSL2 may reach the third string selection line voltage VSSL3, a voltage of the ground selection line GSL may reach the third ground selection line voltage VGSL3, and a voltage of the substrate 111 may reach an erase voltage Vers.

The third ground selection line voltage VGSL3 may be controlled such that the string selection transistors SST1 and SST2 are not erased due to a voltage difference between the string selection lines SSL1 and SSL2 and the substrate 111. For example, the third ground selection line voltage VGSL3 may be controlled to have a level within a specific range on the basis of half an erase voltage Vers.

The third ground selection line voltage VGSL3 may be controlled such that the ground selection transistors GST are not erased due to a voltage difference between the ground selection line GSL and the substrate 111. For example, the third ground selection line voltage VGSL3 may be controlled to have a level within a specific range on the basis of half an erase voltage Vers.

Memory cells MC1 to MC6 may be erased by a voltage difference between the word lines WL1 to WL6 and the substrate 111.

At t4, voltages of the string selection lines SSL1 and SSL2 may start to decrease from the third string selection line voltage VSSL1. A voltage of the ground selection line GSL may start to decrease from the third ground selection line voltage VGSL3. A voltage of the substrate 111 may start to decrease from the erase voltage Vers.

In some embodiments, after voltages of the string and ground selection lines SSL1, SSL2, and GSL are lowered to a ground voltage VSS, at t5, a voltage of the substrate 111 may be lowered to the ground voltage VSS.

As described above, when a voltage of the substrate 111 reaches the target voltage Vtar, the third string selection line voltage VSSL3 may be applied to the string selection lines SSL1 and SSL2. A voltage difference between the string selection lines SSL1 and SSL2 and the substrate 111 may be kept within a specific range.

For example, voltages of the string selection lines SSL1 and SSL2 may be prevented from being increased over a voltage of the substrate 111. Accordingly, programming of the string selection transistors SST1 and SST2 may be prevented. Further, voltages of the string selection lines SSL1 and SSL2 may be prevented from becoming lower by a specific voltage other than a voltage of the substrate 111. Accordingly, erasing of the string selection transistors SST1 and SST2 may be prevented. Further, it is possible to prevent the string selection lines SSL1 and SSL2 from falling into a quasi-on or turn-on state before a voltage of the substrate 111 is transferred to the channel films 114. Accordingly, programming of deterioration of the string selection lines SSL1 and SSL2 due to the GIDL may be prevented.

Likewise, when a voltage of the substrate 111 reaches the target voltage Vtar, the third ground selection line voltage VGSL3 may be applied to the ground selection line GSL. A voltage difference between the ground selection line GSL and the substrate 111 may be kept within a specific range.

For example, a voltage of the ground selection line GSL may be prevented from being increased over a voltage of the substrate 111. Accordingly, programming of the ground selection transistors GST may be prevented. Further, voltages of the ground selection line GSL may be prevented from becoming lower by a specific voltage other than a voltage of the substrate 111. Accordingly, erasing of the ground selection transistors GST may be prevented. Further, it is possible to prevent the ground selection transistors GST from falling into a quasi-on or turn-on state before a voltage of the substrate 111 is transferred to the channel films 114. Accordingly, programming of deterioration of the ground selection transistors GST due to the GIDL may be prevented.

FIG. 22 is a block diagram illustrating a substrate monitor circuit in FIG. 19. Referring to FIG. 22, a substrate monitor circuit 130 may include an up-trimmer 161, a down-trimmer 163, and a comparator 165.

A substrate voltage Vsub may be provided to the up-trimmer 161. The down-trimmer 163 may be connected with a ground terminal. An intermediate node C between the up-trimmer 161 and the down-trimmer 163 may be connected with the comparator 165. The up-trimmer 161 and the down-trimmer 163 may be configured to divide the substrate voltage Vsub. For example, the up-trimmer 161 and the down-trimmer 163 may be configured to have a resistance value. That is, a voltage divided by the up-trimmer 161 and the down-trimmer 163 may be provided to the comparator 135.

In some embodiments, the up-trimmer 161 and the down-trimmer 163 may be configured to have a variable resistance value. For example, the up-trimmer 161 may be configured to adjust a resistance value in response to the first code signal CODE1. The down-trimmer 163 may be configured to adjust a resistance value in response to the second code signal CODE2.

The comparator 165 may compare a voltage of the intermediate node C and a target voltage Vtar to activate a selection signal SE according to the comparison. The selection signal SE may be transferred to a voltage generating circuit 140 b. The voltage generating circuit 140 b may supply the third string selection line voltage VSSL3 to string selection lines SSL1 and SSL2 of a selected memory block BLKa in response to the selection signal SE. That is, a target voltage Vtar may be determined according to a level of a reference voltage Vref and a division rate of the up-trimmer 161 and the down-trimmer 163.

The division rate of the up-trimmer 161 and the down-trimmer 163 may be controlled according to the first and second code signals CODE1 and CODE2. Accordingly, a level of the target voltage Vtar may be varied according to the code signals CODE1 and CODE2.

In FIG. 22, there is exemplarily described such an example that an output of the comparator 165 is used as the selection signal SE. However, a logic block can be further provided which outputs the selection signal SE by adjusting an output of the comparator 165.

FIG. 23 is a circuit diagram illustrating an up-trimmer in FIG. 22. Referring to FIG. 23, an up-trimmer 161 may include plurality of resistors R1 to Rn and a plurality of switches T1 to Tn. In some embodiments, the switches T1 to Tn may be formed of a transistor. However, the inventive concept is not limited thereto.

The resistors R1 to Rn may be connected in series. The resistors R1 to Rn may be connected in parallel with the transistors T1 to Tn, respectively. The transistors T1 to Tn may operate responsive to the first code signal CODE1. In some embodiments, if the transistor T1 is turned on, it may provide a bypass path of the resistor R1. Accordingly, a resistance value of the up-trimmer 131 may decrease. If the transistor T1 is turned off, the bypass path of the resistor R1 may not be formed. Accordingly, a resistance value of the resistor R1 may be reflected to a resistance value of the up-trimmer 131.

A down-trimmer 163 in FIG. 22 may be identical to the up-trimmer 161 except that the second code signal CODE2 is provided to the down-trimmer 163, and description thereof is thus omitted.

As described above, a resistance value of the up-trimmer 161 may be adjusted according to the first code signal CODE1. Further, a resistance value of the down-trimmer 163 may be adjusted according to the second code signal CODE2. As a result, a level of a target voltage Vtar may be varied according to the first and second code signals CODE1 and CODE2.

FIG. 24 is a block diagram illustrating a voltage generating circuit in FIG. 19. Referring to FIGS. 19 and 24, a voltage generating circuit 140 b may include an erase voltage generating 142, a ground selection line driver 143, a string selection line driver 144, and a gate circuit 145.

The erase voltage generator 142 may operate in response to an erase enable signal Een. The erase voltage generator 142 may be configured to generate an erase voltage Vers in response to the erase enable signal Een. The erase voltage Vers may be supplied to a substrate 111 of a memory cell array 110.

The gate circuit 145 may operate in response to the erase enable signal Een and a selection signal SE. When the erase enable signal Een and the selection signal SE are at an active state, the gate circuit 145 may activate an internal signal IS. The internal signal IS may be provided to the ground selection line driver 143 and the string selection line driver 144.

The ground selection line driver 143 may be configured to generate the third ground selection line voltage VGSL3 in response to the internal signal IS. The third ground selection line voltage VGSL3 may be supplied to a ground selection line GSL via an address decoder 120.

The string selection line driver 144 may be configured to generate the third string selection line voltage VSSL3 in response to the internal signal IS. The third string selection line voltage VSSL3 may be supplied to string selection lines SSL1 and SSL2 via the address decoder 120.

With erase methods according to the inventive concept, a ground voltage VSS may be supplied to ground and string selection lines GSL, SSL1, and SSL2. As the ground voltage VSS is supplied to the ground and string selection lines GSL, SSL1, and SSL2, ground and string selection transistors GST, SST1, and SST2 may be prevented from falling into quasi-on and turn-on states.

Further, with the erase method of the inventive concept, voltages of the ground and string selection lines GSL, SSL1, and SSL2 may be controlled from a ground voltage VSS in response to applying of an erase voltage Vers. In some embodiments, a difference between voltages of the string selection lines SSL1 and SSL2 and a voltage of a substrate 111 may be kept within a specific range. Accordingly, it is possible to prevent the ground and string selection transistors GST, SST1, and SST2 from being programmed and erased.

FIG. 25 is a circuit diagram illustrating an equivalent circuit of a memory block in FIGS. 3 to 6 according to some embodiments of the inventive concept. Referring to FIGS. 3 to 6 and 25, a memory block BLKa2 may be divided into a plurality of sub blocks along the second direction. Dummy memory cells DMC1 and DMC2 and dummy word lines DWL1 and DWL2 may be provided between sub blocks.

In some embodiments, memory cells MC1 to MC4 of the equivalent circuit BLKa2 may constitute one memory block. At an erase operation, an erase method of the equivalent circuit BLKa2 may be substantially the same as that described with reference to an equivalent circuit BLKa1 in FIG. 7 except that a dummy word line voltage VDWL is supplied to the dummy word lines DWL1 and DWL2 or the dummy word lines DWL1 and DWL2 are floated. The dummy word line voltage VDWL may be higher than a word lie erase voltage Vwe and lower than an erase voltage Vers.

In some embodiments, the memory cells MC1 to MC4 of the equivalent circuit BLKa2 may be divided into sub memory blocks on the basis of dummy memory cells DMC1 and DMC2.

The second and third conductive materials CM2 and CM3 may form the first and second memory cells MC1 and MC2 and the first and second word lines WL1 and WL2, which constitute the first sub block. The fourth and fifth conductive materials CM4 and CM5 may form dummy memory cells DMC1 and DMC2 and dummy word lines DWL1 and DWL2. The sixth and seventh conductive materials CM6 and CM7 may form the third and fourth memory cells MC3 and MC4 and the third and fourth word lines WL3 and WL4, which constitute the second sub block.

The memory block BLKa2 may be erased by the sub block. As described with reference to FIGS. 10 to 24, a word line erase voltage Vwe may be applied to word lines of a selected sub block. Word lines of an unselected sub block may be program inhibited. For example, word lines of an unselected sub block may be floated. An intermediate voltage can be applied to word lines of an unselected sub block. The intermediate voltage may be between the erase voltage Vers and the word line erase voltage Vwe.

The memory block BLKa2 may be erased as described with reference to FIGS. 10 to 24 except that it is erased by the sub block. At an erase operation, a ground voltage VSS may be applied to a ground selection line GSL and string selection lines SSL1 and SSL2. Voltages of the ground and string selection lines GSL, SSL1, and SSL2 may be controlled in response to applying of an erase voltage Vers to a substrate 111.

In some embodiments, examples provide that the memory block BLKa2 is divided into two sub blocks. However, the number of sub blocks is not limited thereto. Further, some example embodiments provide that two dummy word lines DWL1 and DWL2 are provided between sub blocks of the memory block BLKa2. However, the number of dummy word lines DWL1 and DWL2 provided between sub blocks is not limited thereto.

FIG. 26 is a circuit diagram illustrating an equivalent circuit of a memory block in FIGS. 3 to 6 according to some embodiments of the inventive concept. Referring to FIGS. 3 to 6 and 26, cell strings of the same row may share a ground selection line. Cell strings of different rows may be connected with different ground selection lines. That is, ground selection transistors GST may be connected with the first and second ground selection lines GSL1 and GSL2.

The memory block BLKa3 in FIG. 26 may be erased as described with reference to FIGS. 10 to 24 except that a plurality of ground selection lines GSL1 and GSL2 are provided. At an erase operation, a ground voltage VSS may be applied to ground and string selection lines GSL1, GSL2, SSL1, and SSL2. Voltages of the ground and string selection lines GSL1, GSL2, SSL1, and SSL2 may be controlled in response to applying of an erase voltage Vers to a substrate 111.

FIG. 27 is a circuit diagram illustrating an equivalent circuit of a memory block in FIGS. 3 to 6 according to some embodiments of the inventive concept. As compared with an equivalent circuit BLKa1 in FIG. 7, a memory block BLKa4 may further include lateral transistors LTR provided to each cell string.

Referring to FIGS. 3 to 6 and 27, lateral transistors LTR in each cell string may be connected between a ground selection transistor GST and a common source line CSL. Gates of the lateral transistors LTR in each cell string may be connected to a ground selection line GSL together with a gate (or, a control gate) of a ground selection transistor GST therein.

The first conductive materials CM1 may correspond to the first and second ground selection lines GSL1 and GSL2, respectively. If a specific voltage is applied to the first conductive materials CM1, channels may be formed at portions of channel films 114 adjacent the first conductive materials CM1. That is, channels of the ground selection transistors GST may be formed. If the specific voltage is applied to the first conductive materials CM1, channels may be formed at portions of a substrate 111 adjacent the first conductive materials CM1.

The first to third doping regions 311 to 313 may be interconnected to form a common source line CSL. The common source line CSL and channels of memory cells MC1 to MC6 may be electrically connected via channels (e.g., horizontal channels) generated at the substrate 111 by a voltage of the ground selection line GSL and channels (e.g., vertical channels) generated at the channel films 114.

That is, between the common source line CSL and the first memory cells MC1, a transistor perpendicular to the substrate 111 and transistors parallel with the substrate 111 may be provided. The transistors may be driven by the ground selection line GSL. The transistor perpendicular to the substrate may be a ground selection transistor GST, and the transistors parallel with the substrate 111 may be lateral transistors LTR.

FIG. 28 is a circuit diagram illustrating an equivalent circuit of a memory block in FIGS. 3 to 6 according to some embodiments of the inventive concept. As compared with an equivalent circuit BLKa1 in FIG. 7, in each cell string, two ground selection transistors GSTa and GSTb may be provided between memory cells MC1 to MC4 and a common source line CSL, and two string selection transistors SSTa and SSTb may be provided between the memory cells MC1 to MC4 and bit lines BL1 and BL2.

The first conductive materials CM1 may form ground selection transistors GSTa, and the second conductive materials CM2 may form ground selection transistors GSTb. In cell strings of the same row, the ground selection transistors GSTa and GSTb may share a ground selection line GSL. In cell strings of different rows, the ground selection transistors GSTa and GSTb may share a ground selection line GSL. That is, the ground selection transistors GSTa and GSTb may be connected in common with one ground selection line GSL.

The seventh conductive materials CM7 may form string selection transistors SSTa, and the eighth conductive materials CM8 may form string selection transistors SSTb. In cell strings of the same row, string selection transistors SSTa or SSTb having the same height may share one string selection line. String selection transistors SSTa and SSTb having different heights may be connected with different string selection lines.

In cell strings CS11 to CS12 of the first row, the string selection transistors SSTa may share a string selection line SSL1 a, and the string selection transistors SSTb may share a string selection line SSL1 b. In cell strings CS21 to CS22 of the second row, the string selection transistors SST1 a may share a string selection line SSL2 a, and the string selection transistors SSTb may share a string selection line SSL2 b.

There is exemplarily described such an example that each cell string includes two ground selection transistors GSTa and GSTb. That is, the first and second conductive materials CM1 and CM2 may form ground selection transistors GSTa and GSTb. However, the number of ground selection transistors included in each cell string is not limited thereto. For example, each cell string may be configured to include at least one ground selection transistor.

There is exemplarily described such an example that each cell string includes two string selection transistors SSTa and SSTb. That is, the seventh and eighth conductive materials CM7 and CM8 may form string selection transistors SSTa and SSTb. However, the number of string selection transistors included in each cell string is not limited thereto. For example, each cell string may be configured to include at least one string selection transistor.

FIG. 29 is a circuit diagram illustrating an equivalent circuit of a memory block in FIGS. 3 to 6 according to some embodiments of the inventive concept. As compared with an equivalent circuit BLKa5 in FIG. 28, in cell strings of the same row, string selection transistors SSTa and SSTb may share one string selection line.

String selection transistors SSTa and SSTb of cell strings CS11 and CS12 of the first row may be connected in common with the first string selection line SSL1. String selection transistors SSTa and SSTb of cell strings CS21 and CS22 of the second row may be connected in common with the second string selection line SSL2.

As described with reference to FIG. 28, the number of string and ground selection transistors included in each cell string is not limited by those disclosed herein.

FIG. 30 is a circuit diagram illustrating an equivalent circuit of a memory block in FIGS. 3 to 6 according to some embodiments of the inventive concept. As compared with an equivalent circuit BLKa1 in FIG. 7, the first dummy memory cells DMC1 may be provided between memory cells MC2 and ground selection transistors GST. The first dummy memory cells DMC1 may be connected in common with the first dummy word line DWL1. The first conductive materials CM1 may be interconnected to form the first dummy word line DWL1.

The second dummy memory cells DMC2 may be provided between memory cells MC5 and string selection transistors SST. The second dummy memory cells DMC2 may be connected in common with the second dummy word line DWL2. The eighth conductive materials CM8 may be interconnected to form the second dummy word line DWL2.

There is exemplarily described the case that each cell string includes two dummy memory cells DMC1 and DMC2. That is, the first and eighth conductive materials CM1 and CM8 may form dummy memory cells DMC1 and DMC2. However, the number of dummy memory cells included in each cell string is not limited thereto. For example, each cell string may be configured to include at least one dummy memory cell adjacent a ground selection transistor. Further, each cell string may be configured to include at least one dummy memory cell adjacent a string selection transistor.

FIG. 31 is a cross-sectional view taken along a line I-I′ in FIG. 3 according to some embodiments of the inventive concept. Referring to FIGS. 3, 4, and 31, pillars PL11, PL12, PL21, and PL22 may include lower pillars PL11 a, PL12 a, PL21 a, and PL22 a and upper pillars PL11 b, PL12 b, PL21 b, and PL22 b.

The lower pillars PL11 a, PL12 a, PL21 a, and PL22 a may be provided on a substrate 111. The lower pillars PL11 a, PL12 a, PL21 a, and PL22 a may include lower channel films 114 a and lower inner materials 115 a. The lower channel films 114 a may include a semiconductor material having the same conductive type as the substrate 111 or intrinsic semiconductor. The lower channel films 114 a may act as a second-direction body. The lower inner materials 115 a may include an insulation material.

The upper pillars PL11 b, PL12 b, PL21 b, and PL22 b may be provided on the lower pillars PL11 a, PL12 a, PL21 a, and PL22 a. The upper pillars PL11 b, PL12 b, PL21 b, and PL22 b may include upper channel films 114 b and upper inner materials 115 b. The upper channel films 114 b may include a semiconductor material having the same conductive type as the substrate 111 or intrinsic semiconductor. The upper channel films 114 b may act as a second-direction body. The upper inner materials 115 b may include an insulation material.

The lower channel films 114 a and the upper channel films 114 b may be interconnected to form a second-direction body. In some embodiments, semiconductor pads SP may be provided on the lower pillars PL11 a, PL12 a, PL21 a, and PL22 a. The semiconductor pads SP may include a semiconductor material having the same conductive type as the substrate 111 or intrinsic semiconductor. The lower channel films 114 a and the upper channel films 114 b may be coupled via the semiconductor pads SP.

An equivalent circuit of a memory block BLKa may be identical to that BLKa1 in FIG. 7. Accordingly, the memory block BLKa may operate according to methods described with reference to the equivalent circuit BLKa1 in FIG. 7.

In some embodiments, among conductive materials CM1 to CM8 having the first to eighth heights, conductive materials adjacent the semiconductor pads SP may constitute dummy word lines and dummy memory cells. For example, the fourth conductive material CM4, the fifth conductive material CM5, or the fourth and fifth conductive materials CM4 and CM5 may constitute dummy word lines and dummy memory cells.

At this time, an equivalent circuit of a memory block BLKa may be identical to that BLKa2 in FIG. 25. Accordingly, the memory block BLKa may operate according to a method described with reference to the equivalent circuit BLKa2 in FIG. 25.

FIG. 32 is a plan view illustrating a part of one of memory blocks in FIG. 2 according to some embodiments of the inventive concept. In some embodiments, conductive layers of a memory block BLKb are illustrated in FIG. 32. FIG. 33 is a perspective view illustrating a memory block taken along a line I-I′ of FIG. 32. A cross-sectional view of a memory block BLKb taken along a line I-I′ may be identical to that in FIG. 5. Accordingly, the memory block BLKb will be described with reference to FIGS. 5, 32, and 33.

As compared with a memory block BLKa described with reference to FIGS. 3 to 5, pillars PL11, PL12, PL21, and PL22 of the memory block BLKb may be formed to have a square shape. Insulation materials IM may be provided between pillars PL11 and PL12 or PL21 and PL22 of the same row. The insulation materials IM may be extended in the second direction to contact with a substrate 111.

Between the first and second doping regions 311 and 312, conductive materials CM1 and CM8 may be separated into two parts by the pillars PL11 and PL12 and the insulation materials IM. The conductive materials CM1 to CM8 between the pillars PL11 and PL12 and the first doping region 311 may constitute a row of cell strings with the pillars PL11 and PL12. The conductive materials CM1 to CM8 between the pillars PL11 and PL12 and the second doping region 312 may constitute another row of cell strings with the pillars PL11 and PL12.

Between the second and third doping regions 312 and 313, the conductive materials CM1 and CM8 may be separated into two parts by the pillars PL21 and PL22 and the insulation materials IM. The conductive materials CM1 to CM8 between the pillars PL21 and PL22 and the second doping region 312 may constitute another a row of cell strings with the pillars PL11 and PL12. The conductive materials CM1 to CM8 between the pillars PL21 and PL22 and the third doping region 313 may constitute another row of cell strings with the pillars PL21 and PL22.

That is, a row of pillars may constitute two rows of cell strings with separated conductive materials. An equivalent circuit of the memory block BLKb may correspond to one of equivalent circuits BLKa1 to BLKa7 described with reference to FIGS. 25 to 30 except that the number of rows of cell strings is doubled. That is, the memory block BLKb may operate according to a method described with reference to one of equivalent circuits BLKa1 to BLKa7 of FIGS. 7 and 25 to 30.

A cross-sectional view of a memory block BLKb in FIGS. 32 and 33 taken along a line IT may be identical to that in FIG. 31. That is, square-shaped pillars PL11, PL12, PL21, and PL22 may include lower pillars PL11 a, PL12 a, PL21 a, and PL22 a and upper pillars PL11 b, PL12 b, PL21 b, and PL22 b. At this time, an equivalent circuit of the memory block BLKb may correspond to an equivalent circuit BLKa2 described with reference to FIG. 25 except that the number of rows of cell strings is doubled. That is, the memory block BLKb may operate according to a method described with reference to the equivalent circuit BLKa2 in FIG. 25.

FIG. 34 is a block diagram illustrating a memory system according to some embodiments of the inventive concept. Referring to FIG. 34, a memory system 1000 may include a nonvolatile memory device 1100 and a controller 1200.

The nonvolatile memory device 1100 may be substantially identical to one of nonvolatile memory devices 100, 100 b, and 100 c according to some embodiments of the inventive concept. That is, the nonvolatile memory device 1100 may include a plurality of cell strings CS11, CS12, CS21, and CS22 provided on a substrate 111, each cell string including a plurality of cell transistors CT stacked in a direction perpendicular to the substrate 111. The nonvolatile memory device 1100 may be configured to control voltages of string and ground selection lines SSL1, SSL2, and GSL in response to applying of an erase voltage Vers.

The controller 1200 may be coupled with a host and the nonvolatile memory device 1100. The controller 1200 may be configured to access the nonvolatile memory device 1100 in response to a request from the host. The controller 1200 may be configured to control read, program, erase, and background operations of the nonvolatile memory portion 1100, for example. The controller 1200 may be configured to provide an interface between the nonvolatile memory portion 1100 and the host. The controller 1200 may be configured to drive firmware for controlling the nonvolatile memory device 1100.

The controller 1200 may be configured to provide a control signal CTRL and an address ADDR to the nonvolatile memory device 1100. The nonvolatile memory device 1100 may be configured to perform read, erase, and write operations in response to the control signal CTRL and the address ADDR from the controller 1200.

In some embodiments, the controller 1200 may further include constituent elements such as a RAM, a processing unit, a host interface, a memory interface, and the like. The RAM may be used as at least one of a working memory of the processing unit, a cache memory between the nonvolatile memory portion 1100 and the host, or a buffer memory between the nonvolatile memory portion 1100 and the host. The processing unit may control an overall operation of the controller 1200.

The host interface may include the protocol for executing data exchange between the host and the controller 1200. Some embodiments provide that the controller 1200 may communicate with an external device (e.g., the host) via at least one of various protocols such as an USB (Universal Serial Bus) protocol, an MMC (multimedia card) protocol, a PCI (peripheral component interconnection) protocol, a PCI-E (PCI-express) protocol, an ATA (Advanced Technology Attachment) protocol, a Serial-ATA protocol, a Parallel-ATA protocol, a SCSI (small computer small interface) protocol, an ESDI (enhanced small disk interface) protocol, and an IDE (Integrated Drive Electronics) protocol. The memory interface may interface with the nonvolatile memory device 1100. The memory interface may include a NAND interface and/or a NOR interface.

The memory system 1000 may further include an ECC block. The ECC block may be configured to detect and correct an error of data read from the nonvolatile memory device 1100 using ECC. The ECC block may be provided as an element of the controller 1200 or as an element of the nonvolatile memory device 1100.

The controller 1200 and the nonvolatile memory device 1100 may be integrated in a single semiconductor device. The controller 1200 and the nonvolatile memory device 1100 may be integrated in a single semiconductor device to form a memory card. For example, the controller 1200 and the nonvolatile memory device 1100 may be integrated in a single semiconductor device to form a memory card such as a PC (PCMCIA) card, a CF card, an SM (or, SMC) card, a memory stick, a multimedia card (MMC, RS-MMC, MMCmicro), a security card (SD, miniSD, microSD, SDHC), a universal flash storage (UFS) device, or the like.

The controller 1200 and the nonvolatile memory device 1100 may be integrated in a single semiconductor device to form a solid state drive (SSD). The SSD may include a storage device configured to store data in a semiconductor memory. If the memory system 1000 is used as the SSD, it is possible to remarkably improve an operating speed of a host coupled with the memory system 1000.

In some embodiments, the memory system 1000 may be used as computer, portable computer, Ultra Mobile PC (UMPC), workstation, net-book, PDA, web tablet, wireless phone, mobile phone, smart phone, e-book, PMP (portable multimedia player), digital camera, digital audio recorder/player, digital picture/video recorder/player, portable game machine, navigation system, black box, 3-dimensional television, a device capable of transmitting and receiving information at a wireless circumstance, one of various electronic devices constituting home network, one of various electronic devices constituting computer network, one of various electronic devices constituting a telematics network, RFID, or one of various electronic devices constituting a computing system.

In some embodiments, a nonvolatile memory device 1100 or a memory system 1000 may be packed by various types of packages such as PoP (Package on Package), Ball grid arrays (BGAs), Chip scale packages (CSPs), Plastic Leaded Chip Carrier (PLCC), Plastic Dual In-Line Package (PDI2P), Die in Waffle Pack, Die in Wafer Form, Chip On Board (COB), Ceramic Dual In-Line Package (CERDIP), Plastic Metric Quad Flat Pack (MQFP), Thin Quad Flatpack (TQFP), Small Outline (SOIC), Shrink Small Outline Package (SSOP), Thin Small Outline (TSOP), Thin Quad Flatpack (TQFP), System In Package (SIP), Multi Chip Package (MCP), Wafer-level Fabricated Package (WFP), Wafer-Level Processed Stack Package (WSP), and the like.

FIG. 35 is a block diagram illustrating an application of a memory system in FIG. 34. Referring to FIG. 35, a memory system 2000 may include a nonvolatile memory device 2100 and a controller 2200. The nonvolatile memory device 2100 may include a plurality of nonvolatile memory chips, which may be classified into a plurality of groups. Nonvolatile memory chips in each group may communicate with the controller 2200 via a common channel In FIG. 35, there is exemplarily illustrated the case that a plurality of memory chips communicates with the controller 2200 via plural channels CH1 to CHk.

Each nonvolatile memory chip may be configured the same as nonvolatile memory devices 100, 100 a, and/or 100 b according to some embodiments of the inventive concept. That is, each nonvolatile memory chip may include a plurality of cell strings CS 11, CS12, CS21, and CS22 provided on a substrate 111, each cell string including a plurality of cell transistors CT stacked in a direction perpendicular to the substrate 111. Each nonvolatile memory device may be configured to control voltages of string and ground selection lines SSL1, SSL2, and GSL in response to applying of an erase voltage Vers.

As illustrated in FIG. 35, one channel may be connected with a plurality of nonvolatile memory chips. However, the memory system 2000 may be modified such that one channel is connected with one nonvolatile memory chip.

FIG. 36 is a block diagram illustrating a computing system including a memory system described in FIG. 35. Referring to FIG. 36, a computing system 3000 may include a CPU 3100, a RAM 3200, a user interface 3300, a power supply 3400, and a memory system 2000.

The memory system 2000 may be electrically connected with the CPU 3100, the RAM 3200, the user interface 3300, and the power supply 3400. Data provided via the user interface 3300 or processed by the CPU 3100 may be stored in the memory system 2000.

As illustrated in FIG. 36, a nonvolatile memory device 2100 may be connected with a system bus 3500 via a controller 2200. However, the nonvolatile memory device 2100 can be connected directly with the system bus 3500.

The memory system 2000 in FIG. 36 may be a memory system described in FIG. 35. However, the memory system 2000 can be replaced with a memory system 1000 described with reference to FIG. 34.

In some embodiments, the computing system may be configured to include all memory systems 1000 and 2000 described with reference to FIGS. 34 and 35.

According to some embodiments of the inventive concept, it is possible to prevent ground and string selection transistors from being turned on at an erase operation. That is, it is possible to prevent the ground and string selection transistors from being erased or programmed. Accordingly, memory cells may be erased normally.

The above-disclosed subject matter is to be considered illustrative, and not restrictive, and the appended claims are intended to cover all such modifications, enhancements, and other embodiments, which fall within the true spirit and scope. Thus, to the maximum extent allowed by law, the scope is to be determined by the broadest permissible interpretation of the following claims and their equivalents, and shall not be restricted or limited by the foregoing detailed description. 

What is claimed is:
 1. A memory device, comprising: a memory cell array that includes a plurality of cell strings arranged in rows and columns on a substrate, one of the plurality of cell strings including at least one ground selection transistor, a plurality of cell transistors and at least one string selection transistor sequentially stacked on the substrate along a direction perpendicular to the substrate; an address decoder that is connected to the plurality of cell strings; at least one ground selection line, word lines and string selection lines that are configured provide a connection between the address decoder and the plurality of cell strings, the at least one ground selection line connected to ground selection transistors of the plurality of cell strings, the word lines connected to the plurality of cell transistors of the plurality of cell strings, the at least one string selection lines connected to string selection lines of the plurality of cell strings; a read/write circuit that is connected to the plurality of cell strings and that is configured to exchange data with an external device; and a voltage generating circuit that is configured to provide an erase voltage to the substrate and a word line erase voltage to the word lines and a ground selection line voltage to the at least one ground selection line respectively via the address decoder in an erase operation, wherein after the erase voltage and the ground selection line voltage are applied, a first rising slope of a first voltage of the at least one ground selection line is smaller than a second rising slope of a second voltage of the substrate.
 2. The memory device according to claim 1, wherein the voltage generating circuit is further configured to provide a voltage difference between a voltage of the substrate and a voltage of the ground selection line within a predetermined range.
 3. The memory device according to claim 1, wherein the ground selection voltage is a positive voltage lower than the erase voltage.
 4. The memory device according to claim 1, wherein the first rising slope indicates a rising slope of the first voltage from a first time that the first voltage starts to increase to a second time that the first voltage reaches to the ground selection line voltage.
 5. The memory device according to claim 1, wherein the voltage generating circuit is configured to apply the ground selection line voltage at the same time with as the erase voltage is applied.
 6. The memory device according to claim 1, wherein the voltage generating circuit comprises: an erase voltage generator that is configured to generate the erase voltage applied to the substrate in response to an erase enable signal; a delay that is configured to delay the erase enable signal by a predetermined time; and a ground selection line driver that is configured to generate a ground selection line voltage to be supplied to the ground selection line in response to an output signal of the delay.
 7. The memory device according to claim 1, wherein the voltage generating circuit comprises an erase voltage generator that is configured to generate the erase voltage applied to the substrate in response to an erase enable signal.
 8. The memory device according to claim 7, wherein the voltage generating circuit further comprises a delay configured to delay the erase enable signal by a predetermined time.
 9. The memory device according to claim 1, wherein the second rising slope indicates a rising slope of the second voltage from a first time that the second voltage starts to increase to a second time that the second voltage reaches to the erase voltage.
 10. The memory device according to claim 1, further comprising a substrate monitor circuit that is configured to activate a selection enable signal when a voltage level of the substrate reaches a target voltage level, and wherein the voltage generating circuit comprises: an erase voltage generator configured to generate the erase voltage applied to the substrate in response to an erase enable signal; a gate circuit configured to AND the erase enable signal and the selection enable signal; a ground selection line driver configured to generate a ground selection line voltage to be supplied to the ground selection line in response to an output signal of the gate circuit.
 11. The memory device according to claim 1, wherein the voltage generating circuit provides a voltage difference between a voltage of the substrate and the voltages of the string selection lines within a predetermined range.
 12. The memory device according to claim 1, wherein the voltage generating circuit is further configured to provide string selection line voltages to the string selection lines via the address decoder in the erase operation, wherein after the erase voltage and the string selection line voltages are applied, a third rising slope of each of third voltages of the string selection lines is smaller than the second rising slope.
 13. The memory device according to claim 12, wherein the third rising slope indicates a rising slope of the third voltages from a first time that the third voltages start to increase to a second time that the third voltages reaches the string selection line voltage.
 14. The memory device according to claim 12, wherein the memory cell array comprises: a plurality of structures arranged in rows and columns on the substrate and including conductive materials and insulation materials that are alternatingly stacked in the direction perpendicular to the substrate; a plurality of pillars penetrating the plurality of structures in the direction perpendicular to the substrate and contacting the substrate; and a plurality of doping regions provided at the substrate between the rows of the plurality of structures, and wherein the plurality of doping regions form a common source line connected in common with the plurality of cell strings, wherein the plurality of structures and the plurality of pillars constitute the plurality of cell strings.
 15. The memory device according to claim 1, further comprising bit lines that are configured to provide a connection between the read/write circuit and the plurality of cell strings.
 16. A method of erasing in a memory device, the method comprising: applying a ground selection line voltage to a ground selection line connected with ground selection transistors of a plurality of cell strings that each include a plurality of cell transistors stacked in a direction extending away from a substrate; applying string selection line voltages to string selection lines connected with selection transistors of the plurality of cell strings; applying a word line erase voltage to word lines connected with cells of the plurality of cell strings; applying an erase voltage to the substrate; wherein after the erase voltage and the ground selection line voltage are applied, a first rising slope of a first voltage of the ground selection line is smaller than a second rising slope of a second voltage of the substrate.
 17. The method according to claim 16, further comprising: keeping a voltage difference between the second voltage of the substrate and the first voltage of the ground selection line within a predetermined range.
 18. The method according to claim 16, wherein the ground selection line voltage is a positive voltage lower than the erase voltage.
 19. The method according to claim 16, wherein the first rising slope indicates a rising slope of the first voltage from a first time that the first voltage starts to increase to a second time that the first voltage reaches to the ground selection line voltage.
 20. The method according to claim 16, further comprising: providing a voltage difference between the second voltage of the substrate and third voltages of the string selection lines within a predetermined range.
 21. A memory system comprising: a nonvolatile memory device; and a controller configured to control the nonvolatile memory device, wherein the nonvolatile memory device includes a memory cell array that includes a plurality of cell strings arranged in rows and columns on a substrate, one of the plurality of cell strings including at least one ground selection transistor, a plurality of cell transistors and at least one string selection transistor sequentially stacked on the substrate along a direction perpendicular to the substrate; an address decoder that is connected to the plurality of cell strings; at least one ground selection line, word lines and string selection lines that are configured provide a connection between the address decoder and the plurality of cell strings, the at least one ground selection line connected to ground selection transistors of the plurality of cell strings, the word lines connected to the plurality of cell transistors of the plurality of cell strings, the at least one string selection lines connected to string selection lines of the plurality of cell strings; a read/write circuit that is connected to the plurality of cell strings and that is configured to exchange data with an external device; and a voltage generating circuit that is configured to provide an erase voltage to the substrate and a word line erase voltage to the word lines and a ground selection line voltage to the at least one ground selection line respectively via the address decoder in an erase operation wherein after the erase voltage and the ground selection line voltage are applied, a first rising slope of a first voltage of the at least one ground selection line is smaller than a second rising slope of a second voltage of the substrate.
 22. The memory system according to claim 21, wherein the nonvolatile memory device and the controller are included in a memory card.
 23. The memory system according to claim 21, wherein the nonvolatile memory device and the controller are included in a Solid State Drive (SSD). 